A pneumothorax (noo-moe-THOR-aks) is a collapsed lung. A pneumothorax occurs when air leaks into the space between your lung and chest wall. This air pushes on the outside of your lung and makes it collapse. A pneumothorax can be a complete lung collapse or a collapse of only a portion of the lung.

A pneumothorax can be caused by a blunt or penetrating chest injury, certain medical procedures, or damage from underlying lung disease. Or it may occur for no obvious reason. Symptoms usually include sudden chest pain and shortness of breath. On some occasions, a collapsed lung can be a life-threatening event.

Treatment for a pneumothorax usually involves inserting a needle or chest tube between the ribs to remove the excess air. However, a small pneumothorax may heal on its own.


The main symptoms of a pneumothorax are sudden chest pain and shortness of breath. Severity of symptoms may depend on how much of the lung is collapsed.

When to see a doctor

Symptoms of a pneumothorax can be caused by a variety of health problems, and some can be life-threatening, so seek medical attention. If your chest pain is severe or breathing becomes increasingly difficult, get immediate emergency care.

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A pneumothorax can be caused by:

  • Chest injury. Any blunt or penetrating injury to your chest can cause lung collapse. Some injuries may happen during physical assaults or car crashes, while others may inadvertently occur during medical procedures that involve the insertion of a needle into the chest.
  • Lung disease. Damaged lung tissue is more likely to collapse. Lung damage can be caused by many types of underlying diseases, such as chronic obstructive pulmonary disease (COPD), cystic fibrosis, lung cancer or pneumonia. Cystic lung diseases, such as lymphangioleiomyomatosis and Birt-Hogg-Dube syndrome, cause round, thin-walled air sacs in the lung tissue that can rupture, resulting in pneumothorax.
  • Ruptured air blisters. Small air blisters (blebs) can develop on the top of the lungs. These air blisters sometimes burst — allowing air to leak into the space that surrounds the lungs.
  • Mechanical ventilation. A severe type of pneumothorax can occur in people who need mechanical assistance to breathe. The ventilator can create an imbalance of air pressure within the chest. The lung may collapse completely.

Risk factors

In general, men are far more likely to have a pneumothorax than women are. The type of pneumothorax caused by ruptured air blisters is most likely to occur in people between 20 and 40 years old, especially if the person is very tall and underweight.

Underlying lung disease or mechanical ventilation can be a cause or a risk factor for a pneumothorax. Other risk factors include:

  • Smoking. The risk increases with the length of time and the number of cigarettes smoked, even without emphysema.
  • Genetics. Certain types of pneumothorax appear to run in families.
  • Previous pneumothorax. Anyone who has had one pneumothorax is at increased risk of another.


Potential complications vary, depending on the size and severity of the pneumothorax as well as the cause and treatment. Sometimes air may continue to leak if the opening in the lung won't close or pneumothorax may recur.

May 21, 2021
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